The motor responsible for actuating the trimmable horizontal stabilizer (THS) onboard of an aircraft shall not be started under specific circumstances, even though a control signal is initiated by e.g. the pilot in the cockpit of the aircraft which would otherwise cause start of the THS-motor. Such specific circumstances include flight situations in which start of the THS-motor would have an adverse or even catastrophic effect on the flight safety of the aircraft.
The THS-motor is typically controlled by an avionic unit, or the flight control system, which includes two relays (relay 51CE and relay 52CE), and depending on the voltage) (normally 28 V) applied to the driving contacts (the coil contacts) of each of the two relays, start of the THS-motor is inhibited even if control signals from e.g. the cockpit are transmitted via the avionic unit to the two relays. Hence, depending on the voltage applied to the driving contacts of the two relays, the THS-motor cannot be started irrespective of any other control signals being present in the avionic unit.
Flight safety still is and has been of paramount importance. Therefore, frequent maintenance and inspection tests have to be conducted on the aircraft. One of these tests includes testing the electronic control infrastructure of the flight control system which establishes control of the THS-motor. In particular, the objective of these tests is to ensure that a particular voltage is applied to the driving contacts of the two relays included in the avionic unit which establishes control of the THS-motor. Thus, by successful completion of these tests, it can be ensured that start of the THS-motor is inhibited in situations in which it would otherwise have a detrimental effect on the flight safety.
A so-called ESAO (Environmentally Sustainable Airport Operation) system is used during ground tests of the aircraft for simulating predefined flight situations in the electronic flight control system and for double-checking whether individual components of the flight control system are behaving as specified. The ESAO-system initiates control signals which are then transmitted along the conducting paths of the flight control system to the THS-motor. On the basis of the simulation signals provided by the ESAO-system, it must be verified whether the simulation signals are processed by the flight control system in a correct manner and are converted into appropriate control signals for applying correct voltages on e.g. the two relays 51CE and 52CE responsible for controlling the THS-motor.
In particular with regard to flight situations which require inhibition of the start of the THS-motor, the ESAO-system initiates simulation signals as a consequence of which a voltage is applied to the 51CE relay and 52CE relay in order to ensure that the THS-motor cannot be started irrespective of any other control signals that might be initiated on board of the aircraft.
Up to now, the voltage applied to the relays 51CE and 52CE (28 Volt) had to be manually measured. To this end, simulation of different flight situations by means of the ESAO-system was initiated by a first operator, and a second operator being connected to the first operator via a radio communication system, had to be in close proximity to the relays 51CE and 52CE in order to verify that dependent on the simulated flight situations, the voltage applied to the two relays 51CE and 52CE was within a specified range. Thus, these inspection tests required much manpower and were cost-intensive.
It is therefore an object of the invention to provide a testing device which considerably facilitates ground tests of an aircraft, in particular ground tests in the course of which the control logic for controlling the THS-motor is tested.